This mentored career development award will advance the career of Dr. Nandakumar Narayanan towards becoming an independent physician-scientist focused on the mechanism of cognitive dysfunction in Parkinson's disease. Currently, there are no treatments for cognitive dysfunction in Parkinson's disease and the mechanism is unclear. Dr. Narayanan proposes experiments that leverage state-of-the art techniques for selectively recording, disrupting, and stimulating neurons in freely-moving, behaving animals. The proposed research will interrogate the mechanism of cognitive dysfunction in Parkinson's disease. This proposal could inspire new therapeutic strategies for cognitive symptoms of PD based on existing gene therapy, functional neurosurgery and brain stimulation approaches. Dr. Narayanan has a strong neuroscience background with a PhD in neuroscience, and has identified an outstanding mentorship team. His primary mentor will be Dr. Ralph DiLeone, an innovative molecular biologist who will teach him novel tools to unravel neural circuits. In parallel, he will extend his neurological training to master all aspects of carng for patients with Parkinson's disease and with deep-brain stimulation. His training will occur in a vibrant neuroscience community with robust departmental support. From these efforts, he will learn a unique skill set to explore the mechanism of cognitive dysfunction in Parkinson's disease. This mentored career development award will position Dr. Narayanan to translate insights from his basic research to the clinical arena to help patients with Parkinson's disease.